body{
	width: 100%;
	height: auto;
	padding: 0;
	margin: 0 auto;
	position: relative;
}
.download{
	width: 100%;
	height: auto;
	position: absolute;
	background-color: aqua;
	margin: 0 auto;
	display: flex;
	top: 42%; 
	align-items: center;
	justify-content: center;
	animation-iteration-count: infinite;
	animation-delay: 2s;
	animation-duration: 2s;
	animation-name: scaleDownLoad;
}@keyframes scaleDownLoad{/* scaleDownLoad 对应动画名称 */
	0%{
		transform: scale(0.5);
	}
	
	50%{
		transform: scale(0.6);
	}
	
	100%{
		transform: scale(0.5);
	}
}

/* 
	css过渡
	https://blog.csdn.net/weixin_43286995/article/details/128148379
	https://www.codeleading.com/article/62591981142/
 */
.download:hover{
	background-color: blue;
}